Power scaling per chip in semiconductor diode lasers can be provided using a bipolar cascade in which multiple lasers are epitaxially grown monolithically in electrical series on a single substrate, separated by tunnel junctions (TJs). While an N junction bipolar cascade laser could theoretically increase the output power by a factor of N over a conventional single junction device, the brightness in the multi-junction diode laser is generally lower than that of the single junction due to relatively thick spacer layers between laser junctions. For example, the theoretical fast axis near field and far field intensities of conventional single junction and incoherent double junction 885 nm diode lasers are shown in FIGS. 1A-1B as curves 102, 104 and 112, 114, respectively. The far field divergence (see FIG. 1B) of the incoherent double junction diode laser (curve 304) is substantially the same as that of the single junction because the optical modes in the two junctions have no coherence with each other. However, as shown in FIG. 1A, the near field size along a growth direction (fast axis) is much more than twice that of the single junction, due to the insertion of a spacer layer between the two laser junctions to minimize optical modal loss at the TJ. This leads to lower brightness even after the power is doubled in the double junction laser. The specific 885 nm single junction diode laser illustrated in FIGS. 1A-1B has a fast axis brightness of 34.4 W/mm-mrad for 10 W output power, while the incoherent double junction laser has a brightness of 19.1 W/mm-mrad for 20 W output power. Thus, while bipolar laser cascades can provide increased power, such devices exhibit lower brightness than single emitter laser diodes, and thus do not improve over single emitters in many applications such as the pumping of fiber lasers.